Relationships between cerebrospinal fluid GABAergic neurosteroid levels and symptom severity in men with PTSD.

Allopregnanolone and pregnanolone (together termed allo + pregnan) are neurosteroid metabolites of progesterone that equipotently facilitate the action of gamma-amino-butyric acid (GABA) at GABAA receptors. The adrenal steroid dehydroepiandrosterone (DHEA) allosterically antagonizes GABAA receptors and facilitates N-methyl-D-aspartate (NMDA) receptor function. In prior research, premenopausal women with posttraumatic stress disorder (PTSD) displayed low cerebrospinal fluid (CSF) levels of allo + pregnan [undifferentiated by the gas chromatography-mass spectrometry (GC-MS) method used] that correlated strongly and negatively with PTSD reexperiencing and negative mood symptoms. A PTSD-related decrease in the ratio of allo + pregnan to 5α-dihydroprogesterone (5α-DHP: immediate precursor for allopregnanolone) suggested a block in synthesis of these neurosteroids at 3α-hydroxysteroid dehydrogenase (3α-HSD). In the current study, CSF was collected from unmedicated, tobacco-free men with PTSD (n = 13) and trauma-exposed healthy controls (n = 17) after an overnight fast. Individual CSF steroids were quantified separately by GC-MS. In the men with PTSD, allo + pregnan correlated negatively with Clinician-Administered PTSD Scale (CAPS-IV) total (ρ=-0.74, p = 0.006) and CAPS-IV derived Simms dysphoria cluster (ρ=-0.71, p = 0.01) scores. The allo+pregnan to DHEA ratio also was negatively correlated with total CAPS (ρ=-0.74, p = 0.006) and dysphoria cluster (ρ=-0.79, p = 0.002) scores. A PTSD-related decrease in the 5α-DHP to progesterone ratio indicated a block in allopregnanolone synthesis at 5α-reductase. This study suggests that CSF allo + pregnan levels correlate negatively with PTSD and negative mood symptoms in both men and women, but that the enzyme blocks in synthesis of these neurosteroids may be sex-specific. Consideration of sex, PTSD severity, and function of 5α-reductase and 3α-HSD thus may enable better targeting of neurosteroid-based PTSD treatments.

5α-dihydroprogesterone concentrations and synthesis in non-pregnant mares.

In vivo and in vitro evidence indicates that the bioactive, 5α-reduced progesterone metabolite, 5α-dihydroprogesterone (DHP) is synthesized in the placenta, supporting equine pregnancy, but its appearance in early pregnancy argues for other sites of synthesis also. It remains unknown if DHP circulates at relevant concentrations in cyclic mares and, if so, does synthesis involve the non-pregnant uterus? Jugular blood was drawn daily from cyclic mares (n = 5). Additionally, ovariectomized mares (OVX) and geldings were administered progesterone (300 mg) intramuscularly. Blood was drawn before and after treatment. Incubations of whole equine blood and hepatic microsomes with progesterone were also investigated for evidence of DHP synthesis. Sample analysis for progesterone, DHP and other steroids employed validated liquid chromatography-tandem mass spectrometry methods. Progesterone and DHP appeared a day (d) after ovulation in cyclic mares, was increased significantly by d3, peaking from d5 to 10 and decreased from d13 to 17. DHP was 55.5 ± 3.2% of progesterone concentrations throughout the cycle and was highly correlated with it. DHP was detected immediately after progesterone administration to OVX mares and geldings, maintaining a relatively constant ratio with progesterone (47.2 ± 2.9 and 51.2 ± 2.7%, respectively). DHP was barely detectable in whole blood and hepatic microsome incubations. We conclude that DHP is a physiologically relevant progestogen in cyclic, non-pregnant mares, likely stimulating the uterus, and that it is synthesized peripherally from luteal progesterone but not in the liver or blood. The presence of DHP in pregnant perissodactyla as well as proboscidean species suggests horses may be a valuable model for reproductive endocrinology in other exotic taxa.

A possible role for progesterone metabolites in human parturition.

There has been a recent resurgence of interest in the role of progesterone in the maintenance of human pregnancy and the onset of labour, following recent reports of its use to prevent preterm labour in high-risk patients. One possible mechanism by which progesterone might contribute to uterine quiescence is through the actions of its metabolites. This article provides a brief overview of progesterone in human pregnancy and an outline of progesterone metabolism in the various reproductive tract tissues as well as the evidence for actions of progesterone metabolites in pregnancy.

Injury elicited increase in spinal cord neurosteroid content analyzed by gas chromatography mass spectrometry.

The effects of spinal cord injury (SCI), combined with castration and adrenalectomy, and of progesterone (PROG) treatment on neurosteroid levels and steroidogenic enzyme expression were investigated in the adult male rat spinal cord (SC). Steroid levels were quantified by gas chromatography/mass spectrometry in SC and plasma, and mRNAs of enzymes by quantitative real-time RT-PCR. The levels of pregnenolone (PREG), PROG, 5alpha-dihydroprogesterone, 3alpha,5alpha-tetrahydroprogesterone increased in SC 75 h after transection without significant increase in the plasma. After combined adrenalectomy and gonadectomy, significant levels of PREG and PROG remained in the SC, suggesting their local biosynthesis. In the SC of adrenalectomized and gonadectomized rats, there was an increase of PREG 24 h after SCI, followed at 75 h by a concomitant increase in its direct metabolite, PROG. These observations are consistent with a sequential increase of PREG biosynthesis and its conversion to PROG within the SC in response to injury. However, no significant change in P450-side chain cleavage and 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase mRNA levels was observed after SCI. Systemic PROG treatment after SCI, resulted in a very large increase in PROG, 5alpha-dihydroprogesterone, and 3alpha,5alpha-tetrahydroprogesterone in both plasma and SC. Furthermore, high levels of 3beta,5alpha-tetrahydroprogesterone were detected in SC, whereas their plasma levels remained barely detectable. Because the ratio of reduced metabolites to PROG was 65-times higher in SC than in the plasma, it appears likely that reduced metabolites mainly originated from local biosynthesis. Our results strongly suggest an important role for locally biosynthesized neurosteroids in the response of the SC to injury.